Arelation between ms and mo given in the tools below does not hold at ms = 7 and greater. consider a 1000 km segment of the san andreas fault. how many ms = 8.5 earthquakes would you expect to occur along this 1000 km segment during a period of 200 years? assume that the brittle zone of the plate is 20 km thick (the deepest earthquakes recorded along the san andreas fault are at 20 km depth). also assume a 6 cm/year plate slip rate. we know that there were two such earthquakes along the san andreas in the last 200 years, one in 1857 and one in 1906. how does your estimate of the number of such events compare to this observation? if it differs greatly, speculate on why it differs.

tools: log(mo) = ms + 18.6 in dyne-cm

you will need an estimate of fault zone shear modulus (take a near surface crystal value computed from the shear wave velocity (3.5 km/sec) and density (2.7 gm/cm^3) in the mid to lower crust. be careful with your units and unit conversions.